Modal verbs 2
SHOULD / ABLE / ALLOWED
SHOULD
- is normally used in the present to express some important change in the future:
• I think you should go to bed now. It's too late.
- it can be also used in the past. It adds "have” + 3rd form of the verb:
• I should have done it yesterday.
CAN / BE ABLE TO
- CAN is used only in the present. If you want to use the idea of can also in the past, use BE ABLE TO:
• I wasn't able to work. I was so tired!
- but BE ABLE TO can be also used in the present. It stresses ONE'S ABILITY:
• I'm not able to get up before 5 am.
MAY / BE ALLOWED TO
- MAY is used only in the present. If you want to use the idea of may also in the past, use BE ALLOWED TO:
• I wasn't allowed to enter the area. It was prohibited.
- but BE ALLOWED TO can be also used in the present. It stresses PERMISSION:
• Are you allowed to read the documents?